This invention relates to hole plugs and, more particularly, to a nuclear steam generator wrapper closure assembly and method of installing means for plugging access holes in the wrapper section of a nuclear steam generator.
Steam generators, which may be used in a nuclear steam supply system, may have access holes located in the outer shell and wrapper of the steam generator for providing a passageway into the interior of the steam generator. During operation of the steam generator, the wrapper internal access holes are plugged. The outer shell access hole is sealed with a cover, which is not connected to the wrapper access hole plug.
To plug the access hole of the wrapper, an oblong plate is inserted through a corresponding oblong access hole in the wrapper of the steam generator, rotated by 90.degree., and held in place against the inside of the wrapper by a second oblong plate, a retaining nut, and a locking tab washer. However, to insure that disassembly of the plug does not occur during operation of the steam generator, alignment of the oblong plates during installation of the plug is time consuming. Also, the installation of the plug into the steam generator is time consuming and there is potential for dropping loose components into the interior of the steam generator.
Therefore, what is needed is a nuclear steam generator wrapper closure assembly which provides a positive alignment of components during assembly and which provides a means for minimizing the possibility of loose components entering the tube bundle area of the steam generator.